Motor-wattmeter for three-phase alternating currents.



No. 637,473. Patented m v. 2|, I899.

J. A. MULLINGER. MOTOR WATTMETEB FOR THREEYPI'IASE ALTERNATING GURRENTS.

(Application filed Aug. 31, 1898.) (No Model.) 3 Sheets-Shut l.

No. 637,473. mm Nov. 2|, I899.

JQA. MULL INGER.

MOTOR WATTMETER FOR THREE PHASE ALTERNATING CURRENTS.

(Application filed Aug. 31, 1898.) (No Model.) 3 Sheets-Sheet 2.

No. 637,473. Patented Nov. 2|, I899.

J. A. MULLINGER. MOTOR WATTMETEB FOR THREE PHASE ALTERNATING GUBRENTS.

(Application filed Aug. 31, 1898.) I (No Model.) 3 Sheets-Sheet 3,

'mz mums PETERS 60., mow-Luna. wnsmnown, nv cv UNITED STATES PATENTGrinch.

JULIUS ADOLF MoLLINeER, OF NUREMBERG, GERMANY.

MOTOR-WATTMETER FOR THREE-PHASE ALTERNATING CURRENTS.

SPECIFICATION forming part of Letters Patent No. 637,473,datedNovemberbl, 1899.

Application filed August 3 1, l. 8 9 8.

T0 aZZ whom it may concern:

Be it known that I, J ULIUs ADOLF MoL- LINGER, electrical engineer, asubject of the German Emperor, residing at Nuremberg, in the Kingdom ofBavaria, German Empire, have invented a new and useful Improvement inMotor -Wattmeters for Three-Phase Alternating-Currents, of which thefollowing is a specification.

My invention relates to motor-meters based upon the principle laid downby Ferraris', and has for its object to provide a simple arrangement ofapparatus for measuring, indicating, and recording the actual energytransmitted by a three-phase alternating-current system.

Investigations made by Behn-Eschenburg and O. B. Shallenberger haveshown that the total energy consumed in a three-phase system, whatevermay be the load, can be measured by two meters of the induction type, soarranged that the series coil of the first meter is inserted in thefirst branch of the main line, the series coil of the second meter inthe second branch of the main line, the shunt field-magnet of the firstmeter being in quadrature between the first and third mains, and theshunt field-magnet in the second meter being in quadrature between thesecond and third mains.

The present invention has for its object the giving to shuntmagnet-fields of such a me-. ter system the proper phase relations. Inorder to obtain this, I arrange the shunt fieldmagnets of the two metersso that their phase displacement is sixty degrees and combine with thesame a choking-coil having a phase displacement of sixty degrees, thearrangement being such that the shunt-magnet coils are connected at oneend to all of the mains and at the other end to a point intermediate themains.

My invention is illustrated in the accompanying drawings, in which-Figure 1 is a diagram of a three-phase system with resistances in starconnection. Fig. 2 is a clock diagram showing the relations of thecurrents and. electromotive forces prevailing in the three-phase system.Fig. 3 is a diagram of the connections for a motorwattmeter forathree-phase system. Fig. 3 is a diagram illustrating a former knownmethod of measuring the energy which is Serial No. 689,903. (No model.)

consumed in a three-phase system by means of two wattmeters. Fig. 3illustrates the arrangement of a meter based upon the principle ofFerraris according to the present invention, in combination with theconnections illustrated by Fig. 3. Figs. 4 and 5 are diagrams showinggraphically the value and relations of the currents and pressures for agiven instance.

When three inductive resistances W W W of similar construction areconnected to the three mains I II III, Fig. 1, on one side and on theother to a point 0, then the prevailing pressure (2 e 6 at the ends ofthe resistances have to the pressures E E E prevailing between the mainsI II III the relation shown in the diagram Fig. 2. It is here seen thatE toward e as well as E toward 6 is displaced by thirty degrees. If theresistances W W W are so proportioned that their currents i i i have alag of sixty degrees to their terminal pressures e e e then the current2' flowing in W is vertical to E and the current 2', flowing in W isvertical to E It is well known (see E Zektrotechm'sche Zeitschrifl,1892, page 73, Behn-Es chenburg) that the total energy consumed in athree-phase system is measured by two wattmeters, which, according toFig. 3 are inserted in a three-phase system wherein the series coil IIof one wattmeter is inserted in the main I and the pressure-coil W ofsame connected between the mains I and III and excited from E while theseries coil H of the other Wattmeter is inserted in the main I1 and thepressure-coil W of same connected between the mains II and III andexcited from E In order to obtain the result sought, I arrange the shuntfield-magnets W and W of the two meters, Figs. 3 and 3", so that thephase displacement of the currents flowing in their coils is sixtydegrees, combining the coils of the magnets with choking-coils in suchmanner that the shunt magnetic coils W W W are connected at the one endto the mains I II III, respectively, and at the other end united,forming the point 0. By this arrangement a magnetic field in quadraturewith the pressure E is produced in the coil W and similarly a magneticfield in quadrature with the pressure E is produced in the coil w,, aswill be seen from the description and diagram shown in Fig. 2. Now if(according to Fig. 3 the pressure-coilIv fin combination with a seriescoil H inserted in the main line I, be made to act upon a closedsecondary member of conducting metal--as, for example, a disk oreylinderand similarly if the pressure-coil II in combination with aseries coil H inserted in the main line II, be made to act upon anotherclosed secondary member, both disks or cylinders being mounted on thesame rotary axis A and between the permament magnets M and M the saidaxis will rotate with a speed proportional to the energy consumed in thethree -phase system. My measuring device therefore consists of a rotarysecondary member of conducting metal, two series coils inserted in thefirst and second main lines, respectively, two pressure-coils, one ofwhich is connected at the one end to the third main line and acting, to-

gether with a series coil inserted in the first main line, upon the saidrotary secondary member. The other pressure-coil is connected at the oneend to the second main line and acts, together with a series coilinserted in the second main line, upon the said rotary secondary member,a choking-coil IV,, connected at one end to the first main line and atthe other end to the terminals of the two pressure-coils. Further, it iswell known that meters which are based upon the principle of Ferraris,as well as wattmeters, are exact energy-meters if the magnet-field ofthe shunt is situated vertical to E (See American Patent No. 531,809, ofSehallenberger.) From these two facts it results that the energy c011-sumed in a three-phase system maybe measured by two meters which arebased upon the principle of Ferraris if the series coil H of the onemeter is inserted in line I and the series coil of the other meter isinserted in line II, and if the coil H of the first meteris permitted towork with a shunt-coil the magnetfield of which is vertical to E and ifthe coil H, of the second meter is permitted to work with a shunt-coilthe magnet-field of which is vertical to E. It therefore results thatthe energy consumed in a three-phase system may be measured by acombination such as is illustrated in Fig. Therein IV W IV are theabove-described and in Fig. 1 illustrated induction-coils, the currents,and therefore also the magnetisms, of which show a displacement of sixtydegrees with respect to the tensions c 6, 6 IV; works with a series coil11,, which is inserted in line I of a meter based upon the principle ofFerraris. IV works with the series coil H which is inserted in line IIof a second meter of the said kind. Because the magnet-fields of IV andIV are respectively vertical to E and E these meters in unison measurethe energy consumed in the three-phase system. That this arrangementnecessitates the use of shunt-magnet coils IV so arranged that thecurrent flowing in each of the said coils is displaced by sixty degreeswith respect to the impressed electromotive force is a specialadvantage, inasmuch as these in practice can easily be produced, and,what is essential, they use up very little energy, owing to otherreasons, as well as because the actual energy is in the proportion cos.00 0.5 times smaller than the apparent, and therefore a very powerfulexciting current can be used with a very small watt consumption, whichis specially advantageous. IVhen the three resistances IV IV IV haveequal electrical proportions-i. 0., when they take up equal current atequal pressure and these'eurrents have an equal displacement against thepressure-then the three pressures e have a displacement equal towardeach other and thirty degrees toward E. In this case all the shuntsconnected between the mains and the point 0 must have a displacement ofsixty degrees in order that the essential eonditionthat 2', is verticalto E and i vertical to E is complied with. The pressures 6 e, c, thenintersect at the center of the isosceles triangle formed by thepressures E, Fig. 4. Should, however, the three shuntcircuits havedifferent electrical proportions, then the pressures c, taken together,are no longer equal, but have different displacement to E. IVith thisconnection it is, however, possible to comply with the essentialcondition 1' 1. E and 1' L E provided that the three shunt-coils II WIV, do not have equal electrical proportions. This may be shown asfollows: Assuming we have the coils IV and IV and that for IVCoefficient of self-induction. L 3.0 henries,

Resistances. R 800 while for IV R 430 .0. L .8 henries, and that withthe use of these coils of unequal electrical proportions a threephasemeasuring apparatus is to be constructed for an installation workingwith fifty periods, one

hundred alternations. For W i, 7, V 8, 1 m 1, 800 l 17 a displacement 149.5" between current 1' and pressure 6 The impedance shows I, MSW+ 10o3.14 X 3 1.233.

In the same way for IV Tang. 1 2.041.

A displacement (71 2 64 is shown between current i and pressure 6 Theimpedance is I vaw+ 100 X ail 2.8 980.

As 2', must be vertical to E and i vertical to E and 1', is displaced by0 49.5" against e (2 must have a displacement toward E of 7 90 49.5 40.5and e, toward E a displacement of 90 64 26. 6 and a, must therefore havethe positions shown in Fig. 5. I As, however, the three pressures e e 6must intersect at a point P the position of e, and the size of e e 6 areshown by the angle y, and The three side pressures 6 result on thediagram in e, 49.5 millimeters, e 58.0 millimeters, e 67.2 millimeters,

while E E E 100 millimeters. hen, therefore, the pressure of thethree-phase current amounts to one hundred volts, then 58.0 volts willbe present at W and 67.2 at W It is then and only then possible toobtain with the coils W and W from the above-mentioned constantscurrents 1' and 2' which are vertical to E and E respectively. Withthese pressures the following currents How in W and NV c 58.0 1 i 0.0470ampere and 3 I 0.0686 ampere.

i 0.061 ampere and a: 85

1 and a resistance l+tg. q1, 0.061'-/ 1+(11.4

and a coefficient of self-induction of When, therefore, the threeresistances W W W with the unequal electrical constants R 70.6 Q L 2.56henries R 800 .(2 L 3.00 henries R 430 0 L 2.80 henries,

are inserted into a three-phase system in the manner shown in Fig. 3,and 7,, with a series coil H connected in main I, and W with a seriescoil H connected in main II, are each allowed to operate in a Ferrarismeasuring apparatus, then the combination of both measuring apparatuswill show the total electrical energy consumed in the three-phasesystem.

.56 henries.

It is therefore not necessary that the three induction-coils V7 W W haveequal electrical proportions,and with this connection anaccurately-Working measuring apparatus can in many cases be produced,even when W W W have unequal electrical proportions.

In order to measure the three-phase energy with two measuring apparatusarranged as above described, two single measuring apparatus may be madeuse of, with two separate dial-plates and different constants, and addtheir multiplied readings, or it is possible to mechanically couple twoof such measuring instruments of equal constants, so that only onereading results, which includes the sum of the effect of bothinstruments.

In the illustrated arrangements the total series current always runsthrough the coils H and H In the use of the total arrangement, however,nothing is altered if instead of the total current only a part of itruns through the coils themselves and the other part runs throughresistances which lie parallel to the series coil, or if the seriescoils are fed by the secondary coils of two transformers whose primarycoils are inserted, respectively, in line I or line II.

Having thus described my invention, what I claim, and desire to secureby Letters Patent of the United States, is-

1. A motor-wattmeter for three-phase alternating currents consisting oftwo induction-motors having inducing-coils in series relation each withone of the current-mains and secondary inducing-coils connected one tothe third current-main and the other to one of the first-named mains andboth to a shunt resistance connected in circuit with the othercurrent-main, substantially as and for the purpose described.

2. A motor-Wattmeter for three-phase alternating currents consisting oftwo induction-motors having each two sets of actuating-coils, oneconsisting of a series coil excited directly by the current flowing inthe first main and a shunt-coil connected between the third main and aresistance, the other consisting of a series coil excited directly bythe current flowing in the second main and a shunt-coil connectedbetween the same and said resistance and a connection from the saidresistance to the other main, substantially as and for the purposedescribed.

Signed at Nuremberg, in the Kingdom of Bavaria, German Empire, this 13thday of August, A. D. 1898.

JULIUS ADOLF MOLLINGER.

Witnesses:

JAKoB BIERLEIN, OSCAR BOCK.

IIO

